Megger BMM500 User Manual

M

Megger Limited
Archliffe Road, Dover
Kent CT17 9EN England
T [phone]
F [phone]

Megger
PO BOX 9007, Valley Forge
PA 19484-9007 USA
T [phone]
F [phone]

Megger
4271 Bronze Way, Dallas, Texas
75237-1017 USA
T [phone]
T [phone]
F [phone]

Megger SARL
29 Allée de Villemomble
93340 Le Raincy, France
T +33 (1) 43.02.37.54
F +33 (1) 43.02.16.24

OTHER TECHNICAL SALES OFFICES
Toronto CANADA, Mumbai India and BAHRAIN.

Megger products are distributed in 146 countries worldwide.

This instrument is manufactured in the United Kingdom.
The company reserves the right to change the specification or design without prior notice.

Megger is a re g i s t e red trademark

Part No. 6172-697 V02 Printed in England 11HH
www.megger.com

USER GUIDE

GUIDE D’UTILISATEUR

BENUTZERANLEITUNG

GUÍA DEL USUARIO

M

BMM500 Series
Insulation & continuity testers

Contents

Safety Warnings 2
Description 3
Operation 4

Live Circuit warning 4
Voltage testing 4
Auto-shut off 4
Backlight 4
Insulation tests 5
Locking Test Button (ltb) 5
Polarisation Index Te s t i n g 5
Automatic Discharge 6
Zeroing of Test Lead Resistance 7
Possible sources of error 7
Continuity Bleeper 8
Resistance Tests (kΩ) 8
Diode Te s t i n g 8
Voltage Tests (V) 9
Battery Replacement 10
Fuse Checking and Replacement 10
Using the MEGGER SP1
Switched Probe 11

Specification 12

Repair and Warranty 19

1

Symbols used on the instruments are :

Caution, risk of electric shock.

Caution, refer to User Guide.
Equipment protected throughout

by Double Insulation (Class II).
Equipment complies with
current EU Directives.
Equipment must not be
connected to voltage sources
>600V CAT II. Suitable for
electrical installations CAT III
300V to Earth

>600V

2

SAFETY WARNINGS

• Safety Warnings and Precautions must be read and understood before the instrument is used. They
must be observed during use.

• The circuit under test must be de-energised and isolated before connections are made except for
voltage measurement.

• Circuit connections m u s t not be touched during a test.

• After insulation tests, capacitive circuits must be allowed to discharge before disconnecting the test

leads.

• The Live Circuit Warning and Automatic Discharge are additional safety features and should not b e
regarded as a substitute for normal safe working practice.

• Replacement fuses m u s t be of the correct type and rating. Failure to fit the correctly rated fuse will result
in damage to the instrument in the event of an overload.

• Test leads, including crocodile clips, must be in good order, clean and have no broken or cracked
i n s u l a t i o n .

• Ensure that hands remain behind guards of probes/clips when testing.

• U.K. Safety Authorities recommend the use of fused test leads when measuring voltage on high energy

s y s t e m s .

NOTE

THE INSTRUMENTS MUSTONLY BE USED BYSUITABLY TRAINED AND COMPETENTPERSONS

Users of this equipment and/or their employers are reminded that Health and Safety Legislation require them to carry out valid risk assessments

of all electrical work so as to identify potential sources of electrical danger and risk of electrical injury such as from inadvertent short circuits.

Where the assessments show that the risk is significant then the use of fused test leads constructed in accordance with the HSE guidance note

GS38 ‘Electrical Test Equipment for use by Electricians’ should be used.

Description

Congratulations on your purchase of a genuine
Megger insulation/continuity tester. Megger has
over 100 years experience in insulation testing
which is reflected in its product designs. Your
BMM500 has been carefully developed to
address the real needs and benefits of the user.

The Megger BMM500 Series instruments are
battery powered Insulation and Continuity
testers, with a measurement capability from
0,01Ω Continuity to 10GΩ Insulation.

O ffering multi-voltage facilities, the instruments
take full advantage of microprocessor t e c h n o l o g y
and feature a large liquid crystal display
combining digital and analogue readings. T h e
analogue display has the benefit of indicating
trends and fluctuations in readings, while the
digital readout gives direct accurate results. T h e
display is also backlit giving clear visibility even
in low light conditions.

The BMM500 Series instruments have the
unique capability of being able to measure
voltages down to a resolution of 0,1mV. This

gives the user the option to fit a wide variety of
transducers to further enhance the capabilities
of the BMM Series instruments, eg temperature
or humidity measurement.

A customised connector on the top of the
instrument enables the optional Megger SP1
Switched Probe to be used for two handed
probe operation.

The 250V, 500V and 1000V ranges can be
used to test electrical installations in compliance
with BS7671 (16th Edition IEE Wi r i n g
Regulations) IEC364 and HD384, since each
range has a 1mA minimum test current at the
minimum pass values of insulation specified in
these documents. Designed to IEC1010-1 the
BMM500 Series are protected against
connection to a 300V Category III supply. T h e
instruments have a basic accuracy of ±2% at
20°C. The instruments are waterproof and
dustproof to IP54. This helps maintain accuracy
and ensures maximum reliability in harsh
e n v i r o n m e n t s .

3

Operation

Refer to Safety Wa rnings before using
the instrument

Testing is automatically inhibited if:

• An external voltage >55V is present when
switched to any insulation range position

• An external voltage >10V is present on all
other ranges (excluding OFF/V).

The external voltage is indicated on the display,
on insulation ranges an audible bleeper will
sound if a test is attempted.

Live Circuit Wa rn i n g

When more than 25V is applied to the terminals
in the insulation ranges, the instrument defaults
to a voltmeter and gives an audible warning.
On all other switch positions except OFF/V
when approx 10V is applied the default
voltmeter will be activated. Testing will be
inhibited.

Voltage Testing on High Energy Systems

Use extreme care when using or measuring
voltages above 30V, particularly in high energy

systems. Fused test leads are available as
optional accessories for local situations where
increased protection is required.

Auto-shut Off

To conserve battery life, Auto-shut Off (preceded by
a series of bleeps) operates after approx.
10 minutes of instrument inactivity on
insulation, 5 minutes on all other ranges. If the
instrument is switched on whilst holding the

key, the Auto shut-off time is extended to
60 minutes. To restore operation after Auto­shut Off, select OFF followed by the required
switch position.

Note: It is recommended that the instrument is

switched to the OFF position when not

in use.

B a c k l i g h t

The backlight is activated by pressing the

key.The backlight will remain illuminated
for approx. one minute before automatically
switching off to conserve battery life,

4

∼

Operation

alternatively the key can be re-pressed.
Insulation Tests (MΩ) (See fig. 1)

The insulation tests apply a known voltage to
the circuit under test and measure the resulting
leakage current. The circuit under test must be
completely de-energised and isolated before
test connections are made.

Insulation tests are only initiated when the
TEST button is pressed.

1. Set the range switch to the test voltage
required.

2. Connect the test leads, first to the
instrument, and then to the isolated item
under test.

3. Press the TEST button to activate the test
voltage. Take the reading.

4. Release the TEST button at the end of the
test.

5. Any capacitive circuits charged during a test
will automatically discharge. If signific a n t
voltage remains the voltage warning will
occur and the voltage present displayed.

6. Remove the test leads only when no
voltage is indicated.

Locking Test Button (ltb)

When it is desired to do a long insulation test,
the test can be ‘locked on’ by pressing the

key while the test button is held down.
The warning will appear on the display and
both buttons may be released whilst the test
continues. The next press of the test button will
terminate the test.

N o t e : T h e re is a short delay on the first operation

of ‘1000V’ range, each time the range is
selected. This is to prevent accidental
application of 1kV.

Polarisation Index Te s t i n g

Polarisation Index (PI) is the term applied to the
Dielectric Absorption Ratio when resistance
values are measured after 1 minute and again
after 10 minutes. Polarization Index is then the
resistance value after 10 minutes divided by the
resistance value after 1 minute. The test can be
run at any voltage. More detailed information

5

∼

Operation

on PI Testing and value assessment can be
found in Megger Limited publications listed in
the Accessories page.

Automatic Discharge

When the TEST button is released after an
insulation test (or re-pressed if ltb feature is
enabled), a 200kΩ load is automatically
switched across the terminals to discharge the
item under test. Any voltage present will be

indicated on the display so that the discharge
can be monitored.

Typical Terminal Voltage Characteristics

Continuity Testing (Ω) (See fig.2)

The continuity tests are activated when the
probes make contact of less than a few kΩ. The
tests apply a constant current and measure the
resulting volt drop across the circuit under test.
The test operates without the need to press the
TEST button. When the test leads are removed

6

Fig.1

Operation

the reading will hold for a few seconds and then
reset. This range is not suitable for diode
testing since the automatic contact detector will
not be activated when connected to a diode.

1. Set the selector switch to Ω.

2. Connect the test leads.

3. The test will activate automatically.

4. After the test probes are disconnected, the
reading will be held for a few seconds.

Z e roing of Test Lead Resistance

The resistance of the test leads can be nulled
on the continuity range (up to 9,99Ω). The null
information is retained in non-volatile memory
and so will be remembered when the instrument is
switched off.

1. Select the Continuity range.

2. Short the test leads across a known good
conductor using prods.

3. When the reading has stabilised, press the
TEST button. The zero offset symbol
will appear.

4. To release the zero offset press the TEST
button again.

Possible sources of erro r

Measurements and results can be effected by
the following:

• The impedance of operating circuits
connected in parallel

• Impedance such as inductors that vary during
the measurement

• Apoor connection to the circuit under test.

7

Fig.2

Continuity Bleeper

The continuity bleeper sounds continuously
when a resistance below the threshold level is
detected. This can be selected from several
values between 2Ω and 3kΩ. To change the
level press the button. Short bleeps will
sound for values above the threshold but below
approx. 3kΩ

1. Set the selector switch to

2. Connect the test leads.

Display (5Ω level selected): Audible:

<5Ω continuous bleep
<3kΩ short bleep
>3kΩ no bleep

To turn off the audible tone and replace it with a
visual indication of continuity, press the TEST
button whilst switched to the range.

will be displayed momentarily and will
appear when resistances below the threshold
are measured.

Resistance Tests (kΩ)

This is a low voltage (5V) low current (25µA)
test for sensitive electronic equipment. It
operates in the same way as the continuity
ranges.

1. Set the selector switch to kΩ.

2. Connect the test leads.

3. The test will activate automatically.
The resistance range is protected by a high

impedance method and therefore if the
instrument is connected to a live circuit the fuse
will not blow as on the insulation, continuity and
buzzer ranges. The instrument will merely
indicate the applied over-voltage.

Diode Te s t i n g

This range can also be used for diode testing,
the positive terminal being the source of the
test current. A forward biased semi-conductor
junction will typically measure 15 to 30kΩ and
the diode symbol is shown on the display.
A reverse junction will measure much higher.
These features together with the small test

Operation

8

∼

current and wide measurement range(0,01kΩ
to 10000kΩ) make the resistance range very
useful for general purpose testing.

Voltage Tests (V)

If >1V a.c. or d.c. is present at the terminals the
measured voltage is indicated on the display.
The voltage display will function within
specification even if the fuse has blown.

If the voltmeter operation is in question, test the
voltmeter on a known source.

1. Set the selector switch to V.

2. Connect the test leads.

3. After a short settling time, the reading will

be displayed automatically.

To view the frequency of the a.c. V being
measured, press the key. The frequency
will be displayed in the range 16Hz - 460Hz.
To view a.c. V press the key.

Millivolt Tests (mV)

The measured a.c. or d.c. voltage is indicated

on the display.

1. Set the selector switch to mV.

2. Select either ac or dc mV using the
key.

3. Connect the test leads.

4. After a short settle time, the reading will
be displayed automatically.

Measuring Other Parameters

The BMM500 Series can be used to measure
numerous quantities from temperature to
current to windspeed through the use of mV
output probes. Any compatible probe with a
known output ratio can be used. eg: a
temperature probe with output ratio of 1mV/ºC
will cause the display to indicate directly
in ºC Certain probes require zeroing, eg
windspeed anemometer. The mV zero option
described below provides this facility

Z e roing of d.c. mV (no a.c. mV zero facility)

To zero the d.c. mV range, short the leads
together in the d.c. mV position, wait for the
reading to settle and then press the TEST

Operation

9

∼

Operation

button. Up to 9,9mV can be zeroed on the d.c.
mV range. The symbol will appear to
indicate the zero has been adjusted.

1. Select the d.c. mV range.

2. Short the test leads together.

3. When the reading has stabilised, press the
TEST button. The zero offset symbol
will appear.

4. To release the zero offset press the TEST
button again.

Battery Replacement

When the low battery symbol appears, the
cells are nearly exhausted and should be
replaced as soon as possible. Use Alkaline c e l l s
IEC LR6 (AA) or NiCd/NiMH rechargeable. To
install or replace the cells, disconnect the test
leads, switch the instrument to OFF and loosen
the captive screws on the rear of the battery
compartment. Remove the cover and
disconnect the battery holder from the battery
leads. Ensure that the replacement cells are

fitted with the correct polarity in accordance
with the label in the battery holder. Reconnect
the battery holder to the battery leads. Replace
and re-secure the battery compartment cover.
Remove the cells if the instrument is not going
to be used for an extended period of time.

The BMM500 Series incorporates an electronic
contact detector to minimise the chance of
blowing the fuse even if accidentally applied to
a live circuit whilst switched to the continuity
range. In the unlikely event of the fuse needing
replacement, a spare is located under the
battery cover.

Fuse Checking and Replacement

To check the instrument fuse, switch to an
insulation range and press the TEST button.
The symbol will appear if the fuse is
ruptured. To replace the fuse, disconnect the
test leads, switch the instrument OFF and
loosen the captive screws holding the battery
compartment cover in place. Remove the cover
and replace the fuse. Replace and re-secure

10

Operation

the battery compartment cover.

Using the Megger SP1 Switched Pro b e

Operation: T h e Megger S P 1 is an accessory for
designated Megger installation test instruments.
When fitted in the specially designed connector,
in place of the existing ‘Low’ lead, the S P 1 a c t s
as a remote test button to operate the instrument
and as a ‘Low’ probe. This simplifies instrument
control and two-handed probing. The S P 1 i s
suitable for use with M e g g e r insulation test
instruments up to 1kV output test voltage.
S a f e t y : Meets the safety requirements for double
insulation to IEC1010-2-031 (1995), EN61010-2­031 (1995), IEC1010-1 (1995), EN61010-1
(1995) Category III*, 300V phase to earth. T h e
probe is fitted with an internal, non-replaceable
fuse, to protect the user should the probe be
used accidentally in conjunction with a test lead
in the low terminal.

* Relates to transient overvoltage likely to be

found in fixed installation wiring.

Do not use the probe if any part of it is
damaged.

11

Specification

(All quoted accuracies are at +20°C.)

Insulation Ranges

Nominal Test Voltage (d.c.): 2 5 0 V, 500V, 1000V
Test voltage accuracy: +15% maximum on open circuit
Short circuit current: < 2 mA
Test Current on load: 1mAat min. pass value of insulation specified in BS7671, HD384

and IEC364, 2mAmax.

Accuracy Range Full Scale Accuracy

1000V 10GΩ ±2% ±2digits ±0,2% per GΩ
500V 5GΩ ±2% ±2 digits ±0,4% per GΩ
250V 2GΩ ±2% ±2 digits ±0,8% per GΩ

N o t e : Above specifications only apply when high quality silicone leads are being used.

Measuring Range: 0,01MΩ to 10GΩ

(0-100GΩ on analogue scale).

EN61557 Operating range: 0,10MΩ to 1GΩ

12

Specification

Continuity

Measuring Range: 0,01Ω to 99,9Ω

(0-10Ω on analogue scale)
EN61557 Operating range: 0,10Ω to 99,9Ω
Accuracy: ±2% ±2 digits
Open circuit voltage: 5V ±1V
Test current: 210mA ±10mA(0-2Ω)
Zero offset at probe tips: 0,10Ω typical
Lead resistance zeroing: Up to 9,99Ω
Noise rejection: 1V rms 50/60Hz
Buzzer: Selectable: operates at less than 2Ω, 5Ω, 20Ω, 50Ω, 200Ω, 500Ω,

3kΩ approx.

R e s i s t a n c e

Measuring Range: 0,01kΩ to 9,99MΩ

(0 to 100MΩ on analogue scale)
Accuracy: ±3% ± 2digits
Open circuit voltage: 5V ±1V
Short circuit current: 25µA ±5µA

13

Specification

Vo l t a g e

Measuring Range: ±1V to ±600V

(0 to 1000V on analogue scale)
Accuracy: 0-600V d.c. ±2% ±3 digit

0-600V a.c (50/60Hz) ±2% ±3 digits

0-600V 400Hz a.c. ±5% ±3 digits
Input resistance: approx 200kΩ.

Detector Threshold: 1V

M i l l i v o l t s

Measuring Range: ±0,1mV to ±1999mV

(0 to 1000mV on analogue scale)
Accuracy:

0,1mV to 10mV d.c. or a.c. (50/60Hz) ±2% ±5 digits

10mV to 1999mV d.c. or a.c. (50/60Hz) ±2% ±3 digits

0,1mV to 10mV a.c. (16-460 Hz) ±5% ±7 digits

10mV to 1999mV a.c. (16-460 Hz) ±5% ±5 digits
d.c. milliVolts zeroing: Up to 9,9mV
Input resistance: >3MΩ

14

Specification

Basic and service errors for Insulation and
Resistance ranges

The basic error is the maximum inaccuracy of
the instrument under ideal conditions, whereas
the service error is the maximum inaccuracy
taking into effect of battery voltage, temperature,
interference, and system voltage and frequency,
where applicable. After determining the service
e r r o r, we can then calculate the measurement
range. This is the range of measurement over
which the error in service is less than 30% of the
reading. Digital instruments are affected by the
number of digits error – for example a value
0,10Ω measured with the continuity range may
give a display in the range 0,07Ω to 0,13Ω which
is a maximum error of 30%. Therefore the
measurement range measuring low resistance
is 0,10Ω to 99,9Ω. When checking that a
measurement does not exceed a limit, the s e r v i c e
error needs to be taken into account and these
tables enables this to be done quickly and easily.
These will guarantee that the value being
measured is greater than or less than the limit
value specified as appropriate.

Insulation Resistance – MΩ

Limit Min. Limit Min.

Indicated Indicated

Reading Reading
0,10 0,14 2,00 2,12
0,20 0,25 3,00 3,16
0,30 0,35 4,00 4,20
0,40 0,46 5,00 5,24
0,50 0,56
0,60 0,66
0,70 0,77
0,80 0,87
0,90 0,98
1,00 1,08

15

Specification

Continuity Resistance – Ω

Limit Min. Limit Min.

Indicated Indicated

Reading Reading
0,10 0,06 2,00 1,88
0,20 0,15 3,00 2,84
0,30 0,25 4,00 3,80
0,40 0,34 5,00 4,76
0,50 0,44 10,00 9,56
0,60 0,54 20,00 18,8
0,70 0,63 30,00 28,4
0,80 0,73 40,00 38,0
0,90 0,82 50,00 47,6
1,00 0,92 100,00 92,0

S A F E T Y

The instruments meet the requirements for
double insulation to IEC 1010-1 (1995), EN
61010-1 (1995) to Category III*, 300V phase to
earth (ground) without the need for separately
fused test leads. If required, fused test leads are
available as an optional accessory.

* Relates to the transient overvoltages likely to

be met in fixed wiring installations.

Complies with the following parts of EN61557,
Electrical safety in low voltage systems up to
1000V a.c. and 1500V d.c. – Equipment for
testing, measuring or monitoring of protective
m e a s u r e s : -

Part 1 – General requirements
Part 2 – Insulation resistance
Part 4 – Resistance of earth

connection and equi­potential bonding

F U S E

500mA(F) 600V, 32x 6mm Ceramic HBC 10kA
minimum.

E . M . C .

The instruments meet EN 61326-1.

16

Specification

POWER SUPPLY

Battery Type: 6x1,5V Alkaline

cells IEC LR6 type
or 1.2V NiCd or
NiMH
re-chargeable
cells.

Battery Life (typical): 2100 5-sec 1kV

insulation tests
3200 5-sec 500V
insulation tests
4000 5-sec 250V
insulation tests
2700 5-sec
continuity tests
4700 5-sec kΩ
tests

E N V I R O N M E N TAL CONDITIONS

Operating range: -10 to +50°C
Operating humidity: 90% RH at 40°C

max.

Storage temperature
range: -30 to +70°C
Calibration Temperature: +20ºC
Maximum altitude: 2000 m
Dust and water protection: IP54
Temperature coefficient: <0,1% per °C

WEIGHT: 742g
DIMENSIONS: 110mm x 220mm

x 45mm

CLEANING: Wipe with a clean

cloth dampened
with soapy water
or Isopropyl
Alcohol(IPA)

17

S p e c i fic a t i o n

A C C E S S O R I E S

Supplied: Part Number

Test lead set 6220-437
Pouch 6420-124
Switch Test Probe 6220-606

(NA Version only)

Optional:

Fused lead set, FPK8 6111-218
Switch Test Probe SP1 6220-606
Test Record Cards
(Pack of 20) 6111-216

Publications:

‘AStitch in Time’ AVTM21-P8B
‘Testing Electrical
Installations’ 6231-605

18

Specification

Repair and Warranty

The instrument circuit contains static sensitive
devices, and care must be taken in handling
the printed circuit board. If the protection of an
instrument has been impaired it should not be
used, and be sent for repair by suitably trained
and qualified personnel. The protection is likely
to be impaired if, for example, the instrument
shows visible damage, fails to perform the
intended measurements, has been subjected
to prolonged storage under unfavourable
conditions, or has been exposed to severe
transport stresses.

New Instruments are Guaranteed for 3 Years
f rom the Date of Purchase by the User.

Note: Any u nauthori zed pr ior repair or

adjustment will automatically invalidate
the Warranty.

Instrument Repair and Spare Parts

For service requirements for Megger Instruments
c o n t a c t : -

Megger Limited

Archcliffe Road
Dover
Kent CT17 9EN
England
Tel: [phone]
Fax: [phone]

or

Megger

Valley Forge Corporate Center
2621 Van Buren Avenue
Norristown, PA 19403
U.S.A.
Tel: [phone]
Fax: [phone]

or an approved repair company.

19

Repair and Warranty

A p p roved Repair Companies

A number of independent instrument repair
companies have been approved for repair work
on most Megger instruments, using genuine
Megger spare parts. Consult the Appointed
Distributor / Agent regarding spare parts, repair
facilities and advice on the best course of
action to take.

R e t u rning an Instrument for Repair

If returning an instrument to the manufacturer
for repair, it should be sent freight pre-paid to
the appropriate address. A copy of the Invoice
and of the packing note should be sent
simultaneously by airmail to expedite clearance
through Customs. A repair estimate showing
freight return and other charges will be
submitted to the sender, if required, before
work on the instrument commences.

20

MeterCenter 2046 West Peninsula Circle Chandler, AZ 85249 [phone] Website: www.BiddleMegger.com